1. Field of the Invention
This invention relates generally to an exercise machine for performing isolation exercises, and is particularly concerned with a leg exercise machine with a self-aligning pivoting seat.
2. Related Art
The three most widely performed leg exercises are the leg extension, leg curl, and leg press exercise. Between them, these exercises cover all of the lower body's major muscle groups. The leg press is compound movement, requiring movement of multiple joints. The leg extension and the leg curl are isolation exercises, so called because they involve a single joint, the knee; require the movement of just one body part, the lower leg; and target a specific muscle group, specifically the quadriceps in a leg extension and the hamstring in a leg curl. Because only one joint action is involved, isolation exercise machines generally use exercise arms with rotational movement that align the pivoting joint of the user with the pivot axis of the arm. In order to reduce joint stress and prevent injury, the user should be properly positioned and supported when performing such exercises.
Existing isolation movement leg exercise machines generally have a stationary user support or seat. Some leg exercise machines have a relatively flat user seat which puts the user in a slight recline. This is easy for the user to enter and exit but does not provide adequate pre-stretch in the beginning of the exercise. With a sufficient load, the user's hips may tend to lift during the exercise. To counter this, seat belts are sometimes added to keep the user in place, or the seat is placed at a steeper angle. The steep angle makes it difficult for users to exit the machine. Although this type of machine provides ample exercise range at the beginning of the exercise, it can be limited at the top end of the movement.
Some known leg extension and leg curl machines have moving user supports, but it is often difficult for the user to maintain balance on the user support in these machines.